Alright, gonna do my best to break this down as simply as possible for y'all.

THREAD: How Climate Change Works

First I have to start with the natural freeze-thaw cycles of the earth that have been happening for millions of years.

These are called "Milankovich Cycles."
There are 3 and each are partially responsible for freeze-thaw cycles. The first I'll talk about is Tilt (Obliquity).

Tilt refers to the fact that earth is tilted on its axis. This tilt is responsible for the seasons (and the fact that there are more hours of sunlight in the summer and less in the winter). I think a lot of people know about this, but if you don't there's no shame.

Theres a "wobble" to the tilt; over thousands of years the earth teeters back and forth on its axis, so the tilt goes from 21.1 degrees to 24.5 degrees. This cycles about every 41,000 years.

This affects the earth's climate in that when the tilt is at its maximum, each hemisphere is a tilted a little bit more towards/away from the sun, which makes summer and winter slightly more extreme when compared to the seasons during minimum tilt.

The next cycle is Eccentricity - cycle of the earth's orbit around the sun.
The earth doesn't orbit around the sun in a perfect circle, it's actually an ellipse (oval) and it stretches back and forth between more of a circle to more elongated. This happens every ~100,000 years

This affects the earth's climate in that when the orbit is stretched, there is a time in the year where the earth is actually a little bit closer to the sun and a time where it is farther away. This is also influence by Precession.

The next cycle is Precession. This one can be a little hard to understand so don't feel bad if you don't quite get it.

Precession refers to what direction in the universe the tilt is pointing towards. This cycle happens every ~26,000 years.

This affects the climate in that when, for example, summer in the north hemisphere happens while the earth is at its closest to the sun on its orbit, the northern hemisphere receives more solar radiation (sunlight) and the N.H. summer is more extreme.

These cycles are all happening at the same time, and the minimums and maximums of each cycle rarely line up with each other. Their combined effects determine the amount of solar radiation (i.e. sunlight) each part of the earth receives, and so affect the climate (temperature).

So, that is how Earth's NATURAL climate change cycles happen.

Now I'll talk about anthropogenic (human caused/accelerated) climate change.

So, today when we talk about climate change, we're usually referring to anthropogenic climate change. This refers to how human activities (such as burning fossil fuels) affect the rate of heating ON TOP OF the effects from the Milankovich cycles I just talked about.

So you've probably heard of the greenhouse effect. This refers to the way earth's atmosphere acts similar to glass, in that it lets sunlight in but doesn't let all the heat back out. Greenhouse gases in the atmosphere are what holds the heat in.

The main greenhouse gases are CO2 (carbon dioxide), CH4 (methane), H2O gas (water vapor), N2O (nitrous oxide), and CFCs

The last few million years, there has been a set amount in the atmosphere that fluctuates very slowly.

When there are more gg in the atmosphere, more heat is trapped in - higher average temperature of the earth. When there's less, more heat escapes - earth is colder (ice age). Now like I said, these fluctuate on their own VERY slowly over thousands of years.

By burning fossil fuels, we release gg that were trapped in or below the earth's surface into the atmosphere - this makes warming happen faster. There's a thing called carbon sinks. These include all the places in the carbon cycle where carbon is stored.

They are usually very balanced. But human activities have been taking carbon out of some sinks and putting them in others, so the carbon cycle is out of balance.

Some carbon sinks, like forests, capture CO2. Plants "breathe in" CO2 and "breathe out" oxygen.

The northern hemisphere has more land, while the southern hemisphere has more ocean. When it's summer in the northern hemisphere, the plants on land are active, breathing and taking CO2 from the atmosphere. This is why when you look at CO2 levels on a graph, it looks like this

the top of each little /\\ represents winter in the NH, and the bottom represents summer, when plants are active and taking CO2 out of the atmosphere so CO2 levels lower slightly.

On top of burning fossil fuels which add gg to the atmosphere, things such as deforestation reduce the number of plants, which means theres less of them taking in CO2. So the concentration of CO2 rises.

The problem with anthropogenic climate change is that we are causing greenhouse gas levels to rise much faster than they naturally do - and we don't entirely know what this will do to the planet.

It could eventually lead to a runaway greenhouse effect - turning earth into a hot wasteland like venus. We don't know because it's never happened like this before.

When we make predictions about weather patterns, sea level rise, etc., this is based on the rate at which we release gg into the atmosphere and therefore the rate at which the earth is heating.

There are many, many more components to this, and each greenhouse gas has a different life span in the atmosphere and a different amount of heat each molecule keeps in. CH4 holds in more heat than CO2, but it doesn't stay in the atmosphere as long as CO2 does

The earth is getting warmer. This is just a plain fact. I hope this thread helped you understand how that happens naturally, and how human activities are making it happen faster. Feel free to ask questions.

I will eventually add to this to discuss the coriolis effect, albedo effect, and how temp. rises more at the poles than at the equator. But for now, understand that when i say the planet’s warming, i’m talking about the average temperature of the whole planet, not specific spots

For further info: thread on the greenland ice sheet https://twitter.com/raccorns/status/1205968646163615744

thread on methane emissions from the natural gas industry and the popular lie “natural gas is cleaner” https://twitter.com/raccorns/status/1206413188864102400

thread on “sacrifice zones” and the colonialism behind climate change https://twitter.com/raccorns/status/1206801335007531010